Blockage of human arteries is a widespread malady and, as such, represents a significant health concern. Blockages reducing blood flow through the coronary arteries to the heart can cause heart attacks, while blockages reducing blood flow through the arteries to the brain can cause strokes. Similarly, arterial blockages reducing blood flow through arteries to other parts of the body can produce grave consequences in an affected organ or limb.
The build-up of atherosclerotic plaque is a chief cause of arterial blockages reducing arterial blood flow. Consequently, several methods have been introduced to alleviate the effects of plaque build-up restricting the arterial lumen. One such method is a procedure termed angioplasty, which uses an inflatable device positioned in the artery to dilate the lumen at the stenosis. A typical angioplasty device is disclosed in U.S. Pat. No. 4,896,669 to Bhate et al. The angioplasty device of Bhate et al includes an inflatable balloon which is attached to the distal end of a hollow catheter. The proximal end of the catheter is attached to a fluid source, providing fluid communication between the balloon and the fluid source.
To treat an arterial stenosis, the Bhate et al balloon is introduced into the artery in a deflated state and guided through the artery over a guide wire to a position adjacent the stenosis. Fluid from the fluid source is then infused into the balloon via the catheter to inflate the balloon. As the balloon expands, it dilates the lumen of the artery. The balloon is then deflated and removed from the artery.
While effective for dilating the lumen at the stenosis, angioplasty devices such as the Bhate et al device do not remove the plaque from the artery. Consequently, the residual plaque either remains in place at the point of the stenosis or breaks off and migrates to other locations in the blood stream. In either case the plaque remains a continuing threat to create blockages in the circulatory system. To address the shortcomings of angioplasty, a procedure termed atherectomy has been devised which cuts and removes the plaque comprising the stenosis from the blood vessel.
An atherectomy procedure typically includes inserting a guide wire into the affected artery and advancing a hollow cutting device over the wire until the cutting device is positioned adjacent the stenosis. The cutting device is then advanced into the stenosis to cut a channel through the plaque, thereby increasing blood flow through the artery. The resulting plaque fragments are removed from the blood stream by drawing them into the hollow cutting device.
A number of atherectomy devices capable of performing this procedure are known in the art. U.S. Pat. No. 4,895,166 to Farr et al, which is assigned to the same assignee as the present invention, discloses an atherectomy device having a frustum-shaped cutter which is attached to the distal end of a hollow catheter. The cutter has two openings that define two straight, even cutting blades. The cutter is directed through the artery over a guide wire, and it is rotated as it advances into the stenosis, thereby cutting the plaque. Excised plaque enters the openings of the cutter and is subsequently removed through the hollow catheter.
While the Farr et al device is effective for its intended purpose, due to the configuration of the cutter blades, a helically-shaped uncut ridge of plaque is occasionally left on the arterial wall as the rotating cutter advances through the stenosis. This ridge of plaque, along with fibers of plaque which extend from the ridge, can act as a site for future blood clotting and ultimately lead to a restenosis of the affected artery. Accordingly, the present invention recognizes a need to provide an atherectomy device which cuts a channel through a stenosis, wherein the channel extends radially out to the arterial wall and has a smooth bore substantially free of plaque.
It is therefore an object of the present invention to provide an atherectomy cutter assembly that can cut a channel through a stenosis in a blood vessel of a living being. Another object of the present invention is to provide an atherectomy cutter assembly that cuts a channel through an arterial stenosis wherein the channel can be radially expanded to the arterial wall. Finally, it is an object of the present invention to provide an atherectomy cutter assembly which is relatively easy to use and cost-effective to manufacture.